Process for improving the dyeability of polyolefins



United States Patent 3,371,982 PROCESS FOR IMPROVING THE DYEABILITY 0F POLYOLEFINS Abraham Kutner, Newark, Del., assignor to Hercules,

Incorporated, a corporation of Delaware No Drawing. Filed Jan. 29, 1964, Ser. No. 341,093 4 Claims. (Cl. 8-97) ABSTRACT OF THE DISCLOSURE This invention relates to shaped articles of stereoregular polyolefins having improved dyeability and to a process for improving the dyeability of shaped articles of stereoregular polyolefins.

There have been introduced recently to the trade articles made from stereoregular polyolefins having a highly crystalline polymeric structure. Filamentary articles of these polyolefins have potentially wide application in textiles since they possess excellent physical properties, such as, for example, excellent tenacities, superior fatigue and abrasion resistance, and the like. In order for stereoregular polyolefin filamentary articles to enjoy widespread use, however, it is desirable that such articles be dyeable in deep shades in a wide range of colors which are reasonably colorfast when subjected to washing and to drycleaning treatments and are also reasonably stable to light.

The dyeing of articles of stereoregular polyolefins, however, has been recognized as an especially difiicult problem, even more so than with articles of other known synthetic materials, because of the extremely hydrophobic nature of the stereoregular polyolefins and the absence of functional groups in their structure which can serve as dye sites to enable dyestuffs to become firmly attached to the articles. As a consequence, dyeing methods and dyestutfs developed for other materials of a hydrophobic nature have proven to be deficient for dyeing articles of stereoregular polyolefins.

While considerable progress has been made in discovering suitable methods for dyeing articles of stereoregular polyolefins, the fact remains that such articles can be dyed in medium to deep shades with only a few selected dyestuffs, and the lightfastness and colorfastness of these, when subjected to washing and to dry-cleaning treatments, is only marginal. One of such methods concerns incorporating in the polyolefin, oxides, hydroxides, sulfates, or carboxylic acid salts of certain polyvalent metals so as to make the polymer receptive to metal-complexing dyestuffs. Articles of polyolefins so modified, however, are often not uniformly dyeable throughout their cross-section, and the dyed articles often exhibit relatively poor colorfastness to dry-cleaning solvents.

It is an object of the present invention, therefore, to provide articles of improved dyeability having a basis of stereoregular polyolefins.

Another object of this invention is to provide a process for improving the dyeability of stereoregular polyolefin articles so that such articles can be dyed uniformly to deep shades in a wide range of colors of excellent fastness to dry-cleaning solvents. Other objects and advantages of this invention will appear from the following description.

In accordance with the invention, it has been discovered that the dyeability of shaped articles having a basis of stereoregular polyolefins can be improved by treating the article with a hydrolyzable organoaluminum compound and then hydrolyzing the treated article whereby there is produced in situ, distributed substantially throughout the article, a fine dispersion of the hydrolysis product of the organoaluminum compound. Articles treated according to this invention can be dyed uniformly in deep shades, and the dyeings exhibit a vast improvement in colorfastness to dry-cleaning solvents and levelness over similar dyeings on articles of stereoregular polyolefins containing alpminum oxides, hydroxides, carboxylic acid salts, and the like as recommended by the prior art.

This improvement of dyeability, color depth, levelness, and colorfastness of dyeings in accordance with this invention is obtainable with any dyestuif capable of complexing with aluminum compounds and includes those dyestuffs which fully penetrate the fiber as well as those dyestuffs which penetrate the fiber only superficially to produce ring dyeings. As a rule, these dyestuffs are nonionic or only slightly ionized, have limited water solubility under neutral conditions, and have a molecular weight below about 500.

The stereoregular polyolefins employed in this invention are the essentially crystalline polymers of mono-aolefins often called isotactic or syndiotactic polymers. Although any polymer of an u-olefin having at least 2 carbon atoms is suitable, the invention is particularly useful for dyeing articles of polymers of mono-u-olefins having from 3 to 6 carbons, including, for instance, polypropylene, poly(butene-1), poly(pentene-1), poly(3-methylbutene-'1), and poly(4-methylpentene-1).

The aluminum compounds which serve as dyeing aids in accordance with the invention are hydrolyzable organoaluminum compounds having the formula wherein R, R and R are the same or diiferent organic radicals selected from the group consisting of alkyl, aryl, aralkyl, alkaryl, alkoxy, and aryloxy radicals, and wherein at least one R, R or R forms an aluminum-carbon bond. Preferably, R, R and R are phenyl or alkyl radicals containing 1 to 12 carbon atoms. Typical organoaluminum compounds include triethylaluminum, triisobutylaluminum, tri-n-propylaluminum triisopropylaluminurn, trihexylaluminum, trioctylaluminum, tridecylaluminum, tridodecylaluminum, triphenylaluminum, tri-Z-phenethylaluminum, tri-4-octylphenylaluminum, diethylaluminum isobutoxide, diphenylaluminum monoisopropoxide, diethylaluminum monophenoxide, and the like.

The general nature of the invention having been set forth, the following examples illustrate some specific embodiments of the invention. It is to be understood, however, that the invention is not limited to the examples since the invention may be practiced by the use of various modifications and changes within the scope of the invention as described herein.

EXAMPLES 1-7 Continuous filament yarns (210 denier/35 filament) were prepared by melt spinning at 280-285 C. molding powder of stereoregular polypropylene having a birefringent melting point of 167 C. and a reduced specific viscosity of 3.3 (specific viscosity divided by concentration of a 0.1% wt./vol. solution of polymer in decahydronaphthalene at C.). Skeins of the yarns were charged to a vessel, the vessel thoroughly flushed with nitrogen, and sufiicient heptane added to the vessel to cover the yarn. The vessel was then heated to 65-70 C. and a solution of triisobutylaluminum in heptane was added to the vessel in such quantity as to produce a 0.05 molar solution of the triisobutylaluminum. After minutes the solution was withdrawn from the vessel and the yarn (still under N 2) Washed twice with sufficient heptane to cover the yarn. The yarn was then scoured at a :1 liquor to yarn ratio by weight in an aqueous bath containing 0.5% by weight of a nonionic alkylphenoxypoly(ethyleneoxy)ethanol detergent, Igepal CO 630, for 10 minutes at 8090 C., rinsed, and dried. Analysis of the yarn showed that it contained 0.17% aluminum as determined by emission spectroscopy. Tensile strength of the yarn was unchanged over that of the untreated yarn.

Specimens of the aluminum-containing yarn were then dyed with various dyestuffs having the ability to complex with metals at a 40:1 liquor ratio and a dye level of 1% on the weight of yarn fiber (o.w.f.) in an aqueous dye bath containing 1% Igepal CO 630 based on yarn weight and adjusted to a pH of 56. The yarn was introduced into the dye bath at -60 C., the temperature raised to 90-100 C. within 20 minutes, and the dyeing continued for 2, hours. The dye bath was then drained from the dyed yarn specimens and the specimens rinsed well with warm water containing a small amount of Igepal CO 630, scoured at about 85 C. at a 40:1 liquor to yarn ratio by weight in an aqueous bath containing 1% based on yarn weight of Igepal CO 630, rinsed well with warm water, and then dried. For the 4 Chemists andColorists (A.A.T.C.C.) vol. XXXVI, 1960, Howes Publishing Co., Inc., 44 E. 23rd St., New York. For depth of shade, the following rating scale was employed:

0=tint; very slight coloration 1=light shade 2:medium shade 3 deep shade For the dry-cleaning resistance test, a scale of O to 5 was employed having the following significance:

5=no visible fading or loss of color 4=very slight fading or loss of color 3=slight to medium fading or loss of color 2=medium to severe fading or loss of color 1=very severe fading or loss of color 0=complete loss of color TABLE I i C 1 Depth Fastness x in lo D estu 0 or o to ry E l io y Color Cleaning 0.1. Disperse Red 60 Red Violet--. 2+ 4+ o Pink 2 2 Red Violet". 1 2 Blue 2 5 do. -.do 1 3 .do. 2 3 Royal Blue 2 3 Violet Blue... 1 1 Blue Violet 1+ 0 Gray Blue. 2 4 Gray 1 3 -do .do. 1+ 2 (3.1. Disperse Blue 7. Pale Blue. 1 5 do Nil 0 1 do Pale Blue 1 3 0.1. Mordant Orange 14 Orange 2+ 5 o PinkRed.- 1 5 do Orange-Red.. 1+ 5 0.1. Mordant Red II Red. 2 5 0- Violet 1 5 7B do Red 1+ 5 sake of comparison, identical dyeings were made on yarns treated in the same manner as above except that in one set (Control 1) no triisobutylaluminum solution was added to the yarn, and in another set (Control 2) the stereoregular polypropylene was compounded with A1 0 prior to spinning to give a yarn containing 0.13% aluminum and the treatment with aluminum triisobutyl was omitted.

The dyed specimens were compared visually for color and depth of shade and were then subjected to A.A.T.C.C. Dry-Cleaning Test Method -1960 and compared. The above dry-cleaning test is described in the Technical Manual of the American Association of Textile EXAMPLES 8l0 The procedure of Examples 1-7 was repeated except that in these examples the yarn was woven into fabric, the fabric treated with a 0.05 molar solution of triethylaluminum instead of triisobutylaluminum, and the dyeings carried out on swatches of the treated fabric which contained 0.15% aluminum. Data as to color, depth of shade, and dry-cleaning resistance for dyeings of these examples using various metal complexing dyestuffs, as compared with dyeings on controls prepared as in Examples 1-7, are tabulated in Table II. In each of the examples the dyeings on the triethylalummum-containing swatches were completely penetrated, showed good leveling, and had excellent fastness to washing and rubbing.

TABLE II Fastness Example Dyestufi Color Depth to Dry No. Cleaning 8 Azo dye: o-amino-benzoic acid 2-naphthol 2 5 do 1 3 1 3 3 5 pyrazolone. 9A d0 Yellow 1 3 9B -do Yellow-orange. 1 3+ Yellow 2 4 1 3 2 2 EXAMPLES 11-15 The procedure of Examples 8-10 was repeated except that in these examples the yarn was prepared by melt spinningat 280-285 C. a 95:5 alloy of the polypropylene of Examples 1-7 and a copolymer of ethylene and vinyl acetate having a weight ratio of ethylenezvinyl acetate of 71:29, an inherent viscosity at 30 C. (0.25% by weight in toluene) of 0.85, and a melt index (ASTM D-1238-57T) of 15. The yarn of these examples was knit on a standard tubular knitting machine into fabric specimens. The treated fabric contained 0.54% aluminum. Data as to depth of color and dry-cleaning resistance for dyeings of these examples using various dyestulfs, as compared with dyeings on controls which were 6 tions also occur when other hydroxylated liquids are used in place of water. The hydrolysis step can be carried out by spraying, padding, or immersion, and the hydrolyzing reagent can be applied to the stereoregular polyolefin article in any manner known for the application of textile auxiliary agents including the use of super-atmospheric pressure. It will be appreciated that the hydrolysis step need not be carried out as a separate treatment since hydrolysis can be performed in an aqueous dye bath. It is, however, advantageous to carry out the hydrolysis as an independent step since conversion of the organoaluminum compound to the finely divided hydrolysis product yields a very stable polyolefin article having good general dye receptivity which can be conveniently not treated with the triethylaluminum, are recorded in m rketed.

Table III. The articles can be dyed by any of the conventional TABLE III Example Fastness No. Dyestufi Color Depth tpegilrgg 11 .Azo dye: o-aminobenzoic acid 1-(3-ch1orophenyl)-3-{Golden yellow 3 5 Control.... methyl-fi-pyrazolone. Yellow 2 2 12.... A dye: 2-amino-4,5,6-trlchlorophenol- 8-acetam1do- {Purple.-.. 3 5 gontr 2-naphthol. .Ii a. dBoQ; .n :1; (g)

e w Controlflfl} Azo dye. 2 ammoA nitrophenol 2.acetamido phenol g (t) 2-amin0-4-nitrophenol+2-naphthol ..{%g% 1 Q 15 III Reddish Pu'riiiIII 3 5 0.1. MordautViolet26 1 5 *Too pale to test.

As was demonstrated above, the dyeability of shaped articles of stereoregular polyolefins can be improved in accordance with this invention by producing in situ substantially throughout the article a fine dispersion of the hydrolysis product of an organoaluminum compound. Although the exact nature of the in situ hydrolysis product of the present invention is not known, it is postulated that the product may consist of hydrated aluminum oxide and/or hydroxide which is present substantially throughout the polymer in a nonextractable form as a molecular dispersion which presents a maximum number of available dyesites for chelation. Whatever the hydrolysis product may be is immaterial, however. Generally, the greater the aluminum content of the polyolefin article the deeper will be the shade obtainable when such articles are dyed. Good dyeings in deep shades have been obtained when the aluminum content of the article ranges from about 0.05 to about 1.0%, and particularly deep shades have been obtained using about 0.075 to about 0.75% aluminum by weight of the article. However, articles containing even a lesser amount than 0.05% of aluminum are dyeable with aluminum-complexing dyestuffs. For greatest depth of shade, however, the preferred range of about 0.075 to about 0.75% by weight of the article should be used.

The manner in which the hydrolyzable organoaluminum compound is made available for hydrolysis within the article of stereoregular polyolefin is not critical. The stereoregular polyolefin article can be contacted with the organoaluminum compound either batchwise or continuously using the organoaluminum compound in undiluted form or preferably in the presence of an inert liquid. Heat can be applied to assist penetration, but it is, of course, desirable to operate at as low a temperature as possible to minimize degradation of the polymer and, of course, to operate under nonhydrolyzing conditions prior to the actual hydrolysis step.

The hydrolysis of the organoaluminum compound can be carried out in any convenient manner using water or steam so that there is formed in situ substantially throughout the article a fine dispersion of the hydrolysis product of the organoaluminum compound. Similar reac dyeing methods. Normally, filamentary articles are scoured with a detergent prior to dyeing and the dyeing is performed in the presence of deionized water which contains a small amount, from 0.03% to 0.15% by weight, although greater or lesser amounts can be used, of a wetting agent. The article is introduced into the dye bath, and the latter is brought to a boil and maintained there long enough to insure adequate dyeing. The articles are thereafter withdrawn and subjected to a postdyeing detergent scour to remove any unattached dyestuff.

What I claim and desire to protect by Letters Patent is:

1. A process for improving the dyeability of shaped articles of a stereoregular polyolefin comprising treating the article with a hydrolyzable organoaluminum compound and then hydrolyzing the treated article whereby there is produced in situ distributed substantially throughout the article a fine dispersion of the hydrolysis product of the organoaluminum compound.

2. The process of claim 1 wherein the polyolefin is polypropylene.

3. The process of claim 1 wherein the organoaluminum compound is triethylaluminum.

4. The process of claim 1 wherein the organoaluminum compound is triisobutylaluminum.

References Cited UNITED STATES PATENTS 3,164,438 l/1965 Thomas 8-55 3,203,750 8/1965 Carbonell et al. 8-55 FOREIGN PATENTS 247,228 9/1963 Australia. 810,023 3/ 1959 Great Britain. 

